1. Field of the Invention
The present invention relates to a device for indicating the remaining quantity of the recordable portion of recording material mounted in a camera.
2. Description of the Related Art
In a conventional still video camera, an object image is formed at an imaging device which changes the object image signal to a video signal; and the video signal is then recorded on a magnetic disk. This magnetic disk has 50 tracks, for example, and is used in a still camera provided with either a field recording system in which one image is recorded on one track, or with a frame recording system in which one image is recorded on two tracks. In other words, one magnetic disk can image 25 images (photographs) with the frame recording system, and 50 images with the field recording system.
According to a conventional method of indicating the number of recordable parts that can be used in the still camera described above, when a magnetic disk is mounted in the camera, the recorded condition of the tracks is read by a magnetic head, so that the remaining number of recordable tracks is indicated as a numerical value such as "50" or "25" by an indicator. The indicator is provided on a camera body in such a manner that the numerical value can be read by a photographer only when not looking through the view finder of the camera.
It should be noted that, in the case of a still video camera, a magnetic disk can be freely inserted and removed during use, different from the usual camera using a film. Therefore, the magnetic disk is often removed from the camera, and a partially used magnetic disk is often inserted in the camera. Also, in some cases, the first track of the magnetic disk is not used, and further, some tracks are intentionally skipped to make blank tracks.
In the above cases in the prior art, the photographer can not tell whether the magnetic disk is unused or partly used, without observing the indicator; nor can be determined whether or not the magnetic disk includes blank tracks located general midway among the total number of tracks. Further, to determine the number of remaining tracks (the number of tracks used or the number of tracks not used) while photographing, the photographer must observe the indicator provided on the camera body during or after each operation of the camera.
Accordingly, if the attention of the photographer is concentrated on the view finder while photographing, the photographer will not be aware of how many usable tracks remain, and thus may not change the magnetic disk at the right time, and accordingly, may miss the opportunity to take a desired photograph.
Further, even if the number of remaining tracks is the same, the displayed number of tracks is different in the field mode and the frame mode. For example, because only the remaining number of tracks is indicated by a conventional system, the number of recordable tracks may be incorrect if the frame mode is selected.
In a still camera using film as the recording material, the number of frames remaining is indicated by an indicator provided on an outer surface of the camera body; and, therefore, in this case also, if the attention of the photographer is concentrated on the viewfinder of the camera, the photographer may not notice that the number of remaining frames is low, and thus may miss an opportunity to take a desired photograph.
Moreover, in a conventional system, since only the number of frames used is indicated, although film having 24 frames is actually mounted in the camera, the photographer may have forgotten this and thinks that film having 36 frames has been mounted in the camera; in such a case, he will thus be convinced that another 12 frames remain to be used when "24" is indicated at the indicator.